The present invention relates to a gate-type slide valve for use with a molten metal container such as a casting ladle and means for operating the gate valve which can be quickly and accurately mounted at the valve or ladle and removed therefrom.
According to presently employed liquid metal handling arrangements in steel mills for instance, the casting ladle is employed to transfer molten metal from a furnace to a casting or molding station where the molten metal is poured through a gate-type slide valve outlet provided in the bottom of the ladle. In view of the high forces that are required to operate the gate valve, it has become customary to provide servo control devices therefor. Such servo control or operating devices have, in general, employed hydraulically operated cylinder and piston units which are mounted at the ladle or stationary valve element on the one hand and are connected to the slidable valve element on the other hand. Since, however, the casting ladles must be moved about from the furnace to a casting position in a factory, it has been necessary to make the cylinder and piston units removable since it is impractical to provide such units with hydraulic hoses of a length which would afford complete freedom of movement of the casting ladle in the mill. Alternatively, it has been proposed to permanently mount the piston and cylinder arrangement under the casting ladle and to employ quick-connect couplings for the hoses. It is believed, however, that the most widespread practice has been to employ a piston and cylinder unit where the hoses are permanently connected and where the unit can be inserted and detached quickly from the coupling mechanism of the slide valve so as to be removable entirely from the casting ladle.
As is well known, in a casting operation, the casting ladle must often be moved considerable distances between its tapping position at the furnace and the casting positions, and it is only at the casting position that the cylinder and piston unit must be operatively connected to the slide valve of the casting ladle. It is necessary, however, to be able to establish the connection of the cylinder and piston unit with the gate valve in the shortest possible time so as to minimize the danger to which the operators are exposed. It is also, of course, desirable that the disengagement of the piston and cylinder arrangement from the valve be able to be effected rapidly for the same reasons.
Previously employed mounting means for the piston and cylinders have required the insertion of the cylinders from a lateral direction for cooperation or engagement with coupling elements on the slide valve and mounting means on the casting ladle. Such mounting means, however, have required from the personnel high skill and accurate handling of the piston cylinder unit in positioning the latter for engagement with the mounting means of the ladle. In addition, workers have had to stand very close to and beneath the casting ladle itself which in view of obvious dangers is undesirable.
In an attempt to overcome this disadvantage, the use of bayonet-type locking parts have been suggested. These elements, which require rotation of the cylinder-piston unit to effect the interlocking present the danger of inadvertent disengagement if means are not provided to secure these elements in engaged position.
It is an object of the present invention to avoid the foregoing and other disadvantages by providing a coupling means for a gate-type slide valve of a casting ladle wich permits a very rapid and accurate insertion and detachment of the piston-cylinder unit and which requires a much less complex mounting for the unit than has previously been the case.
In attaining these objects, according to the present invention, there is provided a pair of mounting arms on the casting ladle having recesses for receiving pivot pins mounted on the cylinder of the valve operating unit in such a position that when the pivot pins are disposed in the recesses, the weight of the piston-cylinder unit will pivot the unit on the pivot pin to bring a connecting element of the piston rod into engagement with an operating arm of the slide valve. Further, this unbalanced mounting of the cylinder unit on the casting ladle will retain the cylinder unit in a stable position while removal of the unit from the mounting arms can still be rapidly effected.
According to the present invention, not only are the coupling units on the slide valve and the piston rod made to engage through the pivoting movement of the piston and cylinder unit, but also, these same elements are kept in engagement as a result of the weight of the cylinder by providing a torque force that constantly acts about the pivot axis.
In an alternative embodiment, the piston rod of the piston-cylinder unit may be mounted so as to be rotatable about its longitudinal axis as well as axially movable in the cylinder and the coupling member of the movable slide valve would be adapted to effect engagement as a result of the axial and rotational movement of the piston rod. Such an arrangement is particularly useful in circumstances where the position of the coupling member of the slide valve cannot previously be accurately or readily determined so as to ensure coupling of the piston rod end upon pivotal movement of the piston-cylinder unit. Thus, the coupling of the piston-cylinder unit to the slide valve can be achieved in two sequential steps, namely, first by pivoting the piston-cylinder unit on the mounting arms of the casting ladle or the slide valve casing and then by a combined axial and radial movement of the piston rod to effect engagement of the coupling member of the piston rod with the coupling member of the slide valve.
Engagement between the coupling member of the piston rod and the coupling member of the slide valve may be aided and maintained by a torque force acting on the piston rod and tending to rotate the latter in a corresponding direction. Such torque force which constantly acts on the piston rod may be provided by excentrically connecting weights therewith, such as the hoses for circulating cooling fluid through axially extending conduits in the piston rod to cool the latter particularly at its coupling end.
The foregoing and other advantages of the present invention will become apparent as consideration is given to the following detailed description and accompanying drawings, in which: